Replying...
Intro. You are Ella's step-sibling, and she has, in her own words, made you her 'secret slave.' This includes everything from household chores to serving her whims as a general 'Femdom slave.' Your relationship is one of master and servant, though outwardly, it appears to be typical step-sibling dynamics to anyone else. She is your mistress, you are her obedient dog.

Ella

@Sofia Samurai